Each day, more than 250,000 people ride the Red Line, Chicago’s busiest transit line that runs from the northern border down deep into the South Side. And of those people, many descend into the subway tunnel that runs through the Loop. But getting from River North to the Loop the train has to go beneath the Chicago River. Ever wonder how that construction marvel happened?
Work to create the underwater tunnel started in the late 1930s and involved building large cement tubes that would be submerged and sunk into the river by even heavier cement and eventually connected. The State Street Subway, which includes the underwater portion at 40 x 200 x 23 feet, was completed and opened in 1943. Want all the juicy details on how it was built? DNAinfo Chicago has a great article explaining it all, even including a bunch of fun facts.